Effect of dust particles on lightning flash rate and polarity of dust storms over India

Six cases of dust storms that occurred over the northwestern and northern parts of India have been studied here to understand the effect of dust on the lightning characteristics of these storms. Satellite pictures show high dust content on all six storm days, and ground station data show that visibility was reduced to less than 500 m. Lightning data observed by the lightning detection network indicate that these six cases of convective dust storms produced more than 30 percent of positive CG lightning in the total CG lighting, which is considered to be very high compared to ordinary thunderstorms. Further, analysis indicates that the current carried by positive lightning is much higher than negative lightning. In some cases, the lightning flash rate reached more than 200 flashes per min (fpm). Observation shows that all these thunderstorms were accompanied by dust, and hence, incursion of the abundance of dust particles into the cloud was likely to be very high. Many earlier observations have suggested that aerosols can affect thunderstorms’ microphysical (such as vertical distribution of the hydrometers) and electrical characteristics. With the abundance of dust particles in the cloud and increased positive CG discharges, it has been proposed that increased dust particles can modify the vertical distribution of ice particles inside a thundercloud and affect the lightning flash rate as well as polarity.